The Power of Flight Possessed 

 by Birds. 



MOST people are familiar with the apologue of 

 Plato, wherein a representation is given of the 

 qualities best adapted to the modes of life of the 

 animal creation : "To some he gave wings, to show them 

 that their safety is in the air." 



There is a great similarity between the performance of 

 the winged tribe and the fishes in the sea, save that the 

 bird is heavier in comparison with the air than is the fish 

 in comparison with the water. At first sight it might be 

 thought impossible for so huge an animal as the Ostend 

 whale, weighing four hundred and ninety thousand 

 pounds, to swim in the sea, considering that its body, so 

 far as the bones and muscles are concerned, must be 

 considerably heavier than water; yet, by a singular con- 

 trivance, it is at once buoyed up in the sea and rendered 

 so much lighter than water that it floats on trie surface 

 when dead. This is caused by an enormous layer of an 

 oily substance called blubber, immediately under the skin. 

 It is said that in this particular whale the weight of 

 blubber was one-twelfth of the whole body, measuring 

 four thousand gallons; hence the extreme difficulty 

 experienced in diving. 



The contrivance for rendering birds buoyant in the air 

 is totally different, and the celebrated Harvey is reputed 

 to have been the happy discoverer. Air in considerable 

 volume is introduced into the body, though it is not, as in 

 fishes, contained in one cavity, but is distributed amongst 

 numerous cells in various parts of the body. 



The lungs, compared with those of quadrupeds, are 

 rather small, but the air-cells with which they communicate 



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